Why does the Torah add a 'Vav' in the word "ve'Korbano"?
Ba'al ha'Turim: This hints at Nchshon's six descendents, each of whom will be blessed with six B'rachos
See Ba'al ha'Turim. who elaborates and gives additional answers to the question.
Why did the Nesi'im bring the Korbanos that they brought, and why did they bring them in the respective vessels that they did?
Rashi: Refer to 7:19
What kind of flour-offering did the Nesi'im bring?
Rashi: They brought a Minchas Nedavah. 1
And not a Minchas Nesachim - that accompanies another Korban (See Sifsei Chachamim).
What is the significance of the Korbanos that they brought?
From here until Pasuk 17, I am citing the Ramban's third explanation (on Pasuk 2) of the Korbanos brought by Nachshon ben Aminadav and the Keilim in which he brought them. Refer to 7:18:1:3*. What is the significance of ... a. "Ka'arah u'Mizrok"? b. "Sheloshim u'Me'ah"? c. "Mizrak Echad Kesef"? d. "Shiv'im Shekel"? e. "So'les"? f. "Belulah ba'Shemen"? g. "Kesef"?